Comedian Sarah Silverman confesses that one of the reasons her boyfriend Michael Sheen makes a great romantic partner for her is that he doesn’t mind if she uses their real-life relationship quirks as fodder for her standup material.

“I have so much material about him, and he’s always great about it,” Silverman, 45, told PEOPLE as the couple attended a special awards consideration screening of Masters of Sex.

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“One, he’s not going to like inhibit my art and my process, and I appreciate that,” explained Silverman, who’s renowned for her outrageously risqué, scatological, taboo-testing and frequently sexually charged standup routines. “But also because he said, ‘No one will ever believe that it’s true. No one will ever believe that everything you’re saying is exactly true.’ ”

For example, during a recent onstage appearance at a gala in Beverly Hills – with Sheen in the audience – Silverman joked about their bedroom pillow talk. “What I like to do is talk crazy right after sex [rather than during],” she said onstage at the Brady Center Bear Awards Gala two weeks ago. “My boyfriend’s foreign, and I like to get in his face and say, ‘U.S.A. Number One!’ He’s like ‘Number One in what?’ ‘Don’t worry about it. It’s important to us that we’re Number One. Juvenile diabetes.'”

In reality, she explained, there’s a little truth in the punchline. “I have weird verbal tics, post-coital verbal tics. He pointed out recently that before I fall asleep at night, I always say the same thing to him, which I don’t know why but I do, actually. Lately I’ve been saying, ‘You don’t f–king get it,’ right before I fall asleep.”

“It’s fantastic to have her as a partner,” Sheen, 47, told PEOPLE. The actor stars as the pioneering real-life sex researcher William Masters on Masters of Sex, and Silverman has a recurring role as Helen, the baby-craving lesbian partner of Masters’ office manager Betty. Ironically, the two have only shared the screen a handful of times since she joined the series in its second season.

“We’ve only ever done two scenes together,” Sheen pointed out. “So we did say last season, ‘Can we please have a scene together?’ So I gave her a gynecological exam, which was interesting.”

“We’re ships in the night,” Silverman added. “It’s funny because when he’s shooting, we barely see each other. And now, when I’m on the show, we really never see each other. Because when he’s off, that’s when I’m shooting, usually.”

The couple was already an item at the start of the series, and although Silverman topped the producers’ wish list for the planned Helen character early on, they almost didn’t cast her when they realized her personal link to Sheen.

“We met a completely different context, at a show I did,” she revealed. “They had always had me in mind for Helen, and then we started dating and they went, ‘Oh no!’ So I guess they went to Michael and said, ‘We’ve always wanted to offer this [role] to Sarah Silverman, but now she’s your girlfriend. Is that okay, comfortable for you?’ Obviously, he was like, ‘Yeah!’ ”